The transtaganolides and basiliolides compounds 1-3 as shown in Diagram 1, are members of a growing family of natural products isolated from plants belonging to the genus Thapsia. Compounds within this group (e.g., compounds 1a, 1b, and 3a) have been shown to induce rapid mobilization of intracellular Ca2+ stores. This activity has been attributed to the inhibition of calcium ATPases residing within the sarco/endoplasmic reticulum (SERCA-ATPases). Thapsia sp. are also the plant source of the commonly employed and structurally unrelated SERCA-ATPase inhibitor, thapsigargin (compound 4). Furthermore, Oikawa and coworkers have proposed a structure-function relationship to the widely utilized anti-malarial agent artemisinin (compound 5), which has also been proposed to act via ATPase inhibition. Other reports suggest a mode of action independent of ATPase inhibition.
Structurally, the transtaganolide/basiliolide molecules possess a dense array of functionalization and a polycyclic ring system comprised of trans-decalin framework, a bridging lactone (see 1a rings A and B) and an unprecedented cyclic acyl ketene acetal (ring C).

Owning to the interesting biological activity and striking architectures, the transtaganolides (compounds 1 and 2) and basiliolides (compound 3) have inspired significant interest from the synthetic community. Despite these early developments by multiple research groups and the disclosure of these advanced intermediates, total synthesis of transtaganolides or basiliolides has not been reported.